Levels of multidrug resistance (MDR1) P-glycoprotein expression by human breast cancer correlate with in vitro resistance to taxol and doxorubicin

To determine whether multidrug resistance (MDR1) P-glycoprotein (Pgp) expression correlated with clinical MDR1-related drug resistance, we established a protocol for quantitative measurement of Pgp expression and in vitro drug resistance in doxorubicin resistant MCF7 breast cancer cell lines and 359 freshly resected specimens of breast carcinoma. Pgp expression was detected with 4E3, UIC2, and JSB-1 monoclonal antibodies using flow cytometry and immunohistochemistry (IHC). Pgp function was determined using PSC833 in a drug resistance-reversal assay and with a three-dimensional agarose-based extreme drug resistance assay. MCF7 calibrator cell lines expressed Pgp, which was functional and in proportion to the degree of drug resistance. Flow cytometry, UIC2 shift assays, IHC scores, and determination of absorbance products by image analysis were all highly correlated (r > 0.9). Overall Pgp expression increased from 11% in untreated patients to 30% in patients who had previously received chemotherapy. Compared with Pgp-negative tumors, a significant increase in doxorubicin and Taxol resistance was seen for breast cancers that expressed Pgp, regardless of prior treatment. A strong correlation between the degree of Pgp expression and in vitro resistance to Taxol and doxorubicin (but not to 5-fluorouracil) was found when either IHC scores or image analysis-based methods were used to quantify Pgp expression (n = 185, P < 0.0001). The degree of Pgp expression strongly correlated with the degree of drug resistance in the clinical specimens studied. These data suggest that (a) Pgp contributes to clinical MDR1-related drug resistance, and (b) both intrinsic and acquired expression of Pgp in breast cancer may contribute in part to therapeutic failure and relapse.

Footshock stress but not contextual fear conditioning induces long-term enhancement of auditory-evoked potentials in the basolateral amygdala of the freely behaving rat

In this study, rats were bilaterally implanted with electrodes in the amygdala for chronic recording. Auditory click stimulation evoked in the basolateral nucleus a field potential characterized by three positive components: P1, P2 and P3 (peak latencies around: 10, 20 and 30 ms, respectively) which were each followed by three negative components: N1, N2 and N3 (peak latencies around: 13, 30 and 50 ms, respectively). Animals were divided into three groups (context-same, context-different and control). Following footshock administration, animals were either re-exposed to the same conditioning chamber (context-same group) or placed in a different context (context-different group) for electrophysiological and behavioural (evaluation of freezing response) recordings. The two early positive-negative complexes (P1-N1 and P2-N2) increased in amplitude from 2 min to 24 h following footshock in both context-same and context-different groups. No significant difference was observed between these two groups. The demonstration of significantly larger freezing responses in context-same subjects on exposure to the aversive conditioned environment indicated that this similarity of effects was not due to lack of conditioning of context under the experimental conditions chosen. We conclude that footshock stress produces general long-lasting changes in amygdala auditory field potentials that are not significantly affected by contextual fear conditioning.

[Conformational radiotherapy in cancers of the prostate: contribution of pelvic immobilization and new fiducial markers]

PURPOSE

To reduce errors in the positioning of patients treated with external conformal radiotherapy for prostate cancer, we evaluated both the use of an immobilization device and new fiducial markers.

MATERIALS AND METHODS

The immobilization device consisted of an individual mold made of polyurethan foam. Two sets of skin markers located on the anterior tibial surfaces were used to identify the pelvic isocenter. The patient's position was evaluated by orthogonal port films which were then compared with the original simulation film.

RESULTS

Results are presented with respect to orthogonal axes. Comparison with classic procedures without immobilization showed that use of the mold and new fiducial markers led to a decrease in set-up errors which were less than 5 mm.

CONCLUSION

With the use of an immobilization device and optimized techniques for patients' positioning, conformal radiotherapy of prostate cancer is more accurate.

Differential modulation of changes in hippocampal-septal synaptic excitability by the amygdala as a function of either elemental or contextual fear conditioning in mice

Recent data obtained using a classic fear conditioning paradigm showed a dissociation between the retention of associations relative to contextual information (dependent on the hippocampal formation) and the retention of elemental associations (dependent on the amygdala). Furthermore, it was reported that conditioned emotional responses (CERs) could be dissociated from the recollection of the learning experience (declarative memory) in humans and from modifications of the hippocampal-septal excitability in animals. Our aim was to determine whether these two systems ("behavioral expression" system and "factual memory" system) interact by examining the consequences of amygdalar lesions (1) on the modifications of hippocampal-septal excitability and (2) on the behavioral expression of fear (freezing) resulting from an aversive conditioning during reexposure to conditional stimuli (CSs). During conditioning, to modulate the predictive nature of the context and of a discrete stimulus (tone) on the unconditional stimulus (US) occurrence, the phasic discrete CS was paired with the US or randomly distributed with regard to the US. After the lesion, the CER was dramatically reduced during reexposure to the CSs, whatever the type of acquisition. However, the changes in hippocampal-septal excitability persisted but were altered. For controls, a decrease in septal excitability was observed during reexposure to the conditioning context only for the "unpaired group" (predictive context case). Conversely, among lesioned subjects this decrease was observed in the "paired group" (predictive discrete CS case), whereas this decrease was significantly reduced in the unpaired group with respect to the matched control group. The amplitude and the direction of these modifications suggest a differential modulation of hippocampal-septal excitability by the amygdala to amplify the contribution of the more predictive association signaling the occurrence of the aversive event.

Exposure to a conditioned aversive environment interferes with long-term potentiation induction in the fimbria-CA3 pathway

The effect of re-exposure of rats to an aversive environment on the induction of long-term potentiation was investigated in the CA3 region 3 and 12 h after contextual conditioning. Electro-physiological recordings showed that re-exposure of rats to the conditioning chamber produced a significant and long-lasting decrease in population spike amplitude at both post-conditioning delays. High-frequency stimulation of the fimbria induced a large and persistent increase in CA3 population spike amplitude (about 400% of baseline) in animals of control groups and shocked animals that were not re-exposed to the conditioning environment. However, high-frequency stimulation applied during re-exposure of shocked subjects 3 h after the initial exposure resulted in a small and transient increase in population spike amplitude (about 140% of baseline); when applied 12 h after the initial exposure, it produced a persistent depression of the response (-30% of baseline). Behavioural testing indicated that re-exposure of shocked animals to the conditioning environment elicited a qualitatively and quantitatively similar freezing behaviour at both post-conditioning delays (3 or 12 h). In contrast to the long-lasting decrease in CA3 population spike amplitude produced by re-exposure to the aversive environment, the level of freezing behaviour diminished rapidly within 10 min of exposure. These results suggest that, during exposure to a conditioned aversive environment, alterations in fimbria-CA3 neural processing may be dissociated from contextual fear-induced freezing behaviour. In addition, processes underlying long-term potentiation induction in fimbria-CA3 pathway may be opposite to those taking place during hippocampal processing of conditioned aversive contexts.

High dose rate endobronchial brachytherapy: results and complications in 189 patients

The purpose of this study was to determine the benefit of high dose rate endobronchial brachytherapy in the treatment of obstructive lung cancer. Between September 1990 and March 1995, 189 patients with bronchogenic carcinoma were treated with high dose rate endobronchial brachytherapy. Most patients (69.3%) had received prior treatment and presented with symptomatic bronchial obstruction due to either recurrent or residual endobronchial disease. A small group (12%) was medically unfit for either surgical resection or thoracic radiotherapy and benefited from endobronchial brachytherapy alone for small endobronchial tumours. The remainder of the patients had not been treated previously and endobronchial brachytherapy was performed for life-threatening symptoms requiring emergency obstruction relief before other therapy. Treatment was performed weekly and consisted of three to four 8 to 10 Gy fractions at a radius of 10 mm from the centre of the source. Major symptomatic relief was obtained for haemoptysis (74%), dyspnoea (54%), and cough (54%). Complete endoscopic response was observed in 54% of cases. Median survival was 7 months for the entire group. For small, strictly endobronchial tumours, complete response rate was 96%, median survival 17 months, and 30 month survival 46%, with a plateau starting at 18 months. Grade 3 to 4 toxicities occurred at a rate of 17% and included massive haemoptysis (n=13), bronchial stenosis (n=12), soft tissue necrosis (n=8), and bronchial fistula (n=3). By univariate analysis, no factor was found to be predictive of late pulmonary toxicity. The present study confirms the usefulness of endobronchial brachytherapy in alleviating symptoms caused by endobronchial recurrence of bronchogenic carcinoma. In addition, this therapy can be tried with curative intent in patients who present with small endobronchial tumours and are not candidates for other forms of therapy.

Activation of c-Src by receptor tyrosine kinases in human colon cancer cells with high metastatic potential

Recent data suggest that signal transduction may have a critical role in the development and regulation of the metastatic phenotype. Here, we investigated the role of c-Src activation in the process of human colon cancer metastasis to the liver. Our data, derived from two different sets of human colon cancer cell line metastatic variants, suggest that not only do highly-metastatic cells display constitutively elevated c-Src protein kinase activity when compared to poorly metastatic cells, but also that receptor tyrosine kinases participate in the ligand-activation of c-Src above basal levels. Specifically, the epidermal growth factor receptor (EGFR), p185HER2/Neu and the hepatocyte growth factor receptor (c-Met) appear to be linked to the process because they preferentially activate c-Src in highly-metastatic cells. EGFR was found to associate with c-Src in colon cancer cells and specific inhibitors of the EGFR resulted in a reduction of c-Src activity to basal levels. In addition, c-Src transfectants displayed partially-activated EGFRs, suggesting a feedback role for c-Src in the regulation of the EGFR. p185HER2/Neu was also identified in immunocomplexes of c-Src following ligand activation of the EGFR, but only in highly-metastatic cells. Collectively, these observations suggest a paradigm whereby c-Src interacts with multiple cell-surface growth factors in a catalytic fashion for the development of tumor cells with metastatic potential.

Constitutive activation of Stat3 in fibroblasts transformed by diverse oncoproteins and in breast carcinoma cells

Signal transducers and activators of transcription (STATs) were originally identified as key components of signaling pathways involved in mediating responses to IFNs. Previous studies showed that the Src oncoprotein constitutively activates one STAT family member, Stat3. In this study, we investigated STAT activation in a panel of rodent fibroblast cell lines stably transformed by diverse viral oncoproteins. Using a temperature-sensitive mutant of v-Src, we determined that Stat3 is activated within 15 min of shift from nonpermissive to permissive temperature for cell transformation. This finding indicates that v-Src tyrosine kinase activity is required for Stat3 activation and suggests that Stat3 is proximal to signaling initiated by Src. In addition, Stat3 activation is induced by another nonreceptor tyrosine kinase, v-Fps; by polyoma virus middle T antigen, which activates Src family kinases; and by v-Sis, which acts as a ligand for the platelet-derived growth factor receptor. In contrast SV40 large T antigen, which transforms cells through different mechanisms, and the v-Ras and v-Raf oncoproteins, which lie in signaling pathways downstream of tyrosine kinases, do not activate Stat3. We did not detect significant activation of Stat1, Stat5, or Stat6 in fibroblasts transformed by the viral oncoproteins investigated. Moreover, Stat3 is activated in response to epidermal growth factor (EGF) but not heregulins in immortalized normal human breast epithelial cells. Because constitutive activation of c-Src and EGF receptor kinases is associated with the progression of breast cancer, we examined activation of STATs in human cell lines derived from breast carcinomas. We detected constitutive activation of Stat3 in five of nine breast carcinoma cell lines but not in normal breast epithelial cells. Furthermore, experiments with an EGF receptor-specific inhibitor indicated that the constitutive activation of Stat3 in these breast carcinoma cell lines is not necessarily dependent on signaling through the EGF receptor, although EGF stimulation further increases Stat3 activation. Taken together, our results demonstrate that selective activation of Stat3 is a common event during oncogenic transformation that directly or indirectly involves activation of specific tyrosine kinase signaling pathways.

Time-dependent blockade of STP and LTP in hippocampal slices following acute stress in mice

The characteristics of short-term potentiation (STP) and long-term potentiation (LTP) in the CA1 region of hippocampal slices were determined at various times following exposure to acute stress produced by restraint and tail-shock in mice. In slices prepared from control animals, theta-burst stimulation resulted in a large increase in evoked field excitatory postsynaptic potentials (EPSPs) amplitude and slope that remained stable at least up to 30 min after stimulation. Slices prepared 1 h after stress exhibited a marked decrease in the extent of both STP and LTP. STP and LTP magnitude were still significantly decreased 24 h after stress exposure and were completely restored to control levels by 48 h. These results provide evidence for a reversible impairment of STP and LTP in CA1 following an acute episode of stress, and suggest that stress activates processes different from those activated by LTP-inducing stimuli.

Activation of STAT transcription factors by herpesvirus Saimiri Tip-484 requires p56lck

Signal transducers and activators of transcription (STATs) relay signals from activated cell surface receptors directly to the nucleus. Previously, a protein required for T-cell transformation by the DNA tumor virus herpesvirus saimiri (HVS) and designated tyrosine kinase interacting protein (Tip-484) was shown to interact with and dramatically upregulate the activity of p56lck. p56lck is a nonreceptor tyrosine kinase that is essential for signaling by the T-cell receptor and also interacts with the CD4, CD8, and interleukin-2 receptors. The present data show activation of STAT1 and -3 by Tip-484. STAT1 and -3 were also found to complex with glutathione S-transferase-Tip-484 only in the presence of p56lck, and STAT3 was shown to be phosphorylated by the Tip-484-p56lck multiprotein complex in vitro. Infection of T cells with HVS or expression of recombinant Tip-484 significantly increased the DNA-binding activity of the STAT1 and STAT3 transcription factors in nuclear extracts and also increased the phosphorylation of STAT3 in vivo. This is the first report of STAT activation by a DNA tumor virus protein. Moreover, these studies demonstrate that p56lck is required for STAT activation by Tip-484.

Renal angiotensin II receptor regulation in two-kidney, one clip hypertensive rats: effect of ACE inhibition

Local renal and plasma renin-angiotensin systems (RAS) both play an important role in blood pressure regulation during the development of two-kidney, one clip Goldblatt hypertension (2K1C) through their vasoactive component, angiotensin II (Ang II). Our goal was to characterize glomerular and preglomerular vascular Ang II receptors during the different stages of development of hypertension in 2K1C rats (2-, 4-, 8-, and 16-weeks postoperative) using Ang II antagonists [Sar1,Ile8]-Ang II, losartan, and PD 123319 and their regulation after angiotensin-converting enzyme (ACE) inhibition by captopril. Competitive binding studies showed that the only Ang II receptor detected on both glomeruli and preglomerular vessels of all groups (2-, 4-, 8-, and 16-week 2K1C rats, control rats, and captopril-treated rats) was the Ang II type 1 receptor (AT1). Vascular AT1 receptor density (Bmax) was significantly lower in only the 16-week 2K1C group, whereas glomerular Bmax was significantly lower in 2K1C rats at 2-, 4-, and 8-weeks. Vascular and glomerular receptor densities were both significantly higher in captopril-treated rats than in nontreated rats. We therefore conclude that in 2K1C rats, Ang II receptors on preglomerular vessels and glomeruli are regulated differentially during the development of hypertension and after ACE inhibition. Our results suggest that glomerular Ang II receptors are regulated by systemic plasma Ang II levels, whereas vascular Ang II receptors are not. However, when renal and systemic RASs are both blocked, these receptors are upregulated but are no longer differentially regulated.

Cysteine residues in human lysosomal acid lipase are involved in selective cholesteryl esterase activity

Human lysosomal acid lipase (LAL) catalyses the deacylation of triacylglycerol and cholesteryl esters in the acidic lysosomal compartment. Treatment of LAL with the reducing agent dithiothreitol affected the triacylglycerol and cholesteryl esterase activities differentially, suggesting the involvement of cysteine residues in determining substrate specificity. To identify the residues involved, human LAL cDNA, under the control of the T7 promoter and tagged with a herpes simplex virus coding epitope, was specifically mutated in order to introduce single amino acid substitutions of each of the six cysteine residues of mature LAL. All Cys-227 mutants showed selectively decreased activity towards cholesteryl oleate, while preserving that towards trioleylglycerol. Substitutions of Cys-236, Cys-240 and Cys-244 affected catalysis towards the two substrates to a variable degree, depending on the side chain of the amino acid introduced. The replacement of Cys-41 or Cys-188 did not result in the preferential cleavage of either one of the two substrates. These data indicate that Cys-227, Cys-236, Cys-240 and Cys-244 play a crucial role in determining LAL substrate specificity. We propose that these cysteine residues are involved in the hydrolysis of cholesteryl ester by affecting selectively the access of this substrate to the catalytic active site. In addition, the fact that the catalytic activity is never completely abolished in cysteine mutants demonstrates that LAL is not a thiol enzyme.

Fish oil-supplemented feeding does not attenuate warm liver ischemia and reperfusion injury in the rat

Liver ischemia and reperfusion injury is mediated by oxygen free radicals, cytokines, and prostanoids produced by Kupffer cells and infiltrating neutrophils. Fish oil-supplemented diets alter membrane phospholipid composition and modify prostanoids and cytokine production in response to ischemia and reperfusion. This study tested the hypothesis that a fish oil-supplemented diet would attenuate warm liver ischemia and reperfusion injury in the rat. Male Sprague-Dawley rats were fed Vital HN supplemented with either fish oil (FO) or corn oil (CO) by the continuous duodenal infusion for 5 days. Total dietary fat (26% of total calories), caloric intake (70 cal/day), and volume (60 ml/day) were identical between two groups. Plasma eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels increased significantly in rats fed fish oil (0 to 16.3% for EPA and 2 to 12% for DHA). Liver histology was similar in both groups before ischemia. On Day 6, rats were subjected to 60 min of reversible hepatic ischemia. Plasma TNF levels, 1 and 24 hr after reperfusion, were not different between FO and CO rats. Liver injury assessed by bile flow, histology, plasma ALT, and bile glutathione efflux did not differ between groups. We conclude that our fish oil-supplemented enteral diet does not attenuate warm liver ischemia and reperfusion injury in rats.

Contextual conditioned fear blocks the induction but not the maintenance of lateral septal LTP in behaving mice

High-frequency stimulation (HFS) of the fimbria induces long-term potentiation (LTP) in the lateral septum. This study was aimed at investigating the effect of contextual fear conditioning on septal LTP with the use of behaving C57 BL/6 mice as subjects. For the acquisition of contextual fear conditioning, animals were placed in a conditioning chamber, where they were subjected to footshocks (FSs, 0.6 mA); the following day (retention), animals were reexposed to the chamber. Animals from the first group received HFS in their home cages before being submitted to conditioning; animals from the second group were first submitted to conditioning before receiving HFS during reexposure to the conditioning chamber; animals from the third group were submitted to the same regimen as those from the second group, except that no FS was delivered in the conditioning chamber; and animals from the fourth group received FS in the conditioning chamber but were maintained in their home cages the day after for LTP induction. Before conditioning, animals from the first group, placed in a familiar context (home cage), displayed an LTP of the N3 wave of septal field potential. After conditioning, reexposure of these animals to the conditioning chamber produced a transient decrease in the amplitude of N3 but did not interfere with the duration of maintenance of LTP. Conversely, in animals from the second group, when HFS was applied during reexposure to the conditioning chamber the induction of LTP was totally blocked. However, mice from the two other groups (3rd and 4th) displayed normal levels of LTP. Taken together with previous findings, these data suggest that contextual conditioned fear may interfere with certain forms of learning via blockade of hippocampal-septal LTP.

Occupational allergy in saffron workers

Sensitization to the flower of saffron, a plant commonly grown in Spain for commercial purposes, and its clinical significance as an occupational allergen were studied. The prick test and RAST, with saffron pollen, stamen, and pistil extracts, were used to evaluate the cutaneous and specific antibody responses in the studied population. Provocation tests in patients with clinical findings were used to verify the implication of saffron components in these symptoms. Fifty saffron workers were evaluated. Three of them were sensitized to saffron pollen and stamen proteins, giving prick and RAST positive values. One patient presented asthma, showing a positive bronchial provocation test, and two patients rhinoconjunctivitis, showing positive conjunctival provocation tests. Of a general allergic population of 237, 10 patients also presented cutaneous test and IgE positive to saffron. Saffron allergens (from pollen and stamens) were characterized by SDS-PAGE immunoblotting. A relevant allergen of 15.5 kDa with profilinic nature was detected and further purified by high-resolution gel filtration chromatography. No allergenic components were demonstrated in pistils. Cross-reactivity of saffron extracts was evaluated by RAST inhibition with respect to other pollen species commonly causing sensitization in the same area of study. A significant degree of cross-reactivity was demonstrated between saffron and Lolium, Salsola, or Olea. The identification of the protein components involved in the cross-reactions was investigated by blot inhibition.

Using slaughter inspections to evaluate sarcoptic mange infestation of finishing swine

Sarcoptic mange is one of the common swine diseases worldwide. Although mange-free populations can be established with caesarean derived stock, by herd repopulation programmes or by eliminating mange with ivermectin, mange remains prevalent in many countries. Field and experimental studies indicate that hypersensitive mange is detrimental to performance of growing pigs. Typically, producers tolerate mange infestation in their herds and control measures are often haphazard. This tolerance to mange infestation is attributable to the covert nature of the losses (reduced growth rate and feed efficiency without mortality) and to the fact that clinical signs of hypersensitive mange (pruritus) are usually viewed as normal. Lack of tools to evaluate mange severity in pigs and to demonstrate its importance has hindered the efforts of veterinarians to control the disease. Traditionally, veterinarians have used slaughter inspections to assess respiratory diseases such as enzootic pneumonia and atrophic rhinitis. Much of the value of slaughter inspections is as a tool with which veterinarians can educate and motivate their clients to improve disease control measures. The potential for evaluating hypersensitive mange by inspecting slaughtered pigs for lesions of papular dermatitis was recognised some time ago, but quantitative evaluation of the reliability of this approach has been lacking. We have conducted several studies in Australia, the USA, Canada, Europe and Latin America to evaluate associations between Sarcoptes infestation and the severity of papular dermatitis at slaughter, using a simple ordinal scale for classifying carcasses. Our initial field and experimental data in Australia indicated the specificity of localised dermatitis to be in the order of 75-80%, but that the generalised dermatitis was highly specific (> 98%) for mange. Subsequent studies in the US Midwest yielded almost identical results, and indicated that the method may also have some utility for surveillance of mange-free herds. Results from other locations invariably have shown significant associations between dermatitis lesions and mange infestation. Relative to other methods such as skin scrapings and monitoring pruritus, this method is simple and relatively objective, and should be considered for routine inclusion in slaughter inspection protocols.

Nosocomial respiratory syncytial virus infections: prevention and control in bone marrow transplant patients

OBJECTIVE

To assess the effectiveness of a multifaceted infection control strategy in limiting the nosocomial transmission of respiratory syncytial virus (RSV) infection to patients in a bone marrow transplant (BMT) unit.

DESIGN

Before/after trial.

SETTING

University-affiliated tertiary cancer center.

PATIENTS

Adult BMT recipients hospitalized during two consecutive wintertime community outbreaks of RSV infection.

INTERVENTIONS

An infection control strategy against nosocomial RSV infection was implemented in the BMT unit in February 1993. The strategy involved prompt identification, isolation, and cohorting of RSV-infected patients; prompt therapy with aerosolized ribavirin; use of masks and gloves by anyone entering an infected BMT patient's room; screening visitors for respiratory symptoms; restricting visitation by all children under 12 years of age and all family members and other visitors with RSV symptoms; and restricting symptomatic hospital staff from working in the BMT unit.

RESULTS

After implementation of the multifaceted infection-control strategy, there were four cases of nosocomial RSV infection in 3,870 patient days (incidence density, 1.0 case/1,000 patient days) compared with 14 cases of nosocomial RSV infection in 3,152 patient days (incidence density, 4.4 cases/1,000 patient days) during the 1992-1993 RSV season (rate ratio, 4.4; 95% confidence interval [CI95]. 1.4-17.9: P < .01). This decrease in incidence occurred despite a comparable prevalence of community-acquired RSV cases between the two seasons (2.2% vs 3.2% in 1992-1993 and 1993-1994, respectively; prevalence ratio, 0.7; CI95, 0.2-2.1; P = 0.5).

CONCLUSION

Institution of a multifaceted infection control strategy significantly reduced the frequency of nosocomial RSV infection in a high-risk group of adult BMT recipients.

Long-term toxicity and neuropathology associated with the sequencing of cranial irradiation and enhanced chemotherapy delivery

OBJECTIVE

The goal was to evaluate, at 1 year, 75 Long-Evans rats for survival rates and toxicity associated with the sequencing of cranial irradiation and enhanced chemotherapy delivery.

METHODS

Seventy-five Long-Evans rats were randomized into four groups and evaluated at 1 year for survival rates and toxicity associated with the sequencing of cranial irradiation and enhanced chemotherapy delivery. Radiation (2,000 cGy) was administered as a single fraction, by using parallel opposed portals, 30 days before chemotherapy (Group 1), 24 hours before chemotherapy (Group 2), 30 days after chemotherapy (Group 3), or without chemotherapy or without radiation (control group, Group 4). Five subgroups within each treatment group included rats receiving intra-arterially administered methotrexate (1 g/m2) or intravenously administered etoposide (200 mg/m2) combined with intra-arterially administered carboplatin (200 mg/m2), administered with or without osmotic blood-rain barrier disruption, and a group receiving normal saline solution after blood-brain barrier disruption.

RESULTS

There was a significant increase in total toxic effects when the three experimental groups were compared with the control group (P = 0.001, 0.006, and 0.013 for Groups 1, 2, and 3, respectively). All groups receiving radiation and chemotherapy (particularly carboplatin and etoposide) had an increased incidence of hind limb paralysis, resembling experimental allergic neuritis (P = 0.053). Statistical analysis showed a trend toward increased mortality rates in Group 1 (antecedent radiation), compared with the control group (P = 0.082), and an increased incidence of intracerebral calcification (P = 0.019). No differences in mortality rates were observed for Group 2 or 3, compared with the control group.

CONCLUSION

Radiation before chemotherapy was a more toxic sequence and, surprisingly, carboplatin/etoposide administered in combination with radiotherapy was more detrimental than methotrexate. Additional studies are in progress to evaluate the toxicity and efficacy of sequences of cranial irradiation and enhanced chemotherapy in tumor-bearing rats.

Strain reorganizes focal adhesions and cytoskeleton in cultured airway smooth muscle cells

Abnormal mechanical stress on pulmonary structures is associated with increased airway resistance and impaired gas exchange as a result of increased airway smooth muscle (ASM) deposition. Using an in vitro system with cultured ASM cells, we have demonstrated that cyclic deformational strain increases ASM cellular myosin and myosin light chain kinase. To determine if these contractile protein increases were accompanied by ultrastructural changes in cells indicating phenotypic modulation, cells subjected to strain were compared to cells grown under static conditions by transmission electron microscopy (TEM) and fluorescent staining. The strained ASM cells oriented perpendicular to the strain direction were more elongated and contained more actin stress fibers than identical cells grown under physically static conditions. The stress fiber bundles were thicker and reorganized parallel to the long axis of the cell. Marked increases in the numbers and lengths of focal adhesions between the cell membrane and the substratum were found by both TEM and immunostaining for talin. Mechanical strain thus increases organization of cytoskeletal elements in cultured ASM cells. Similar effects in vivo may serve to promote the expression of the contractile phenotype of cultured ASM cells independent of other in vivo factors and alter cell contractility. Increased organization of cytoskeletal elements might also increase the efficiency of signal transduction from the extracellular matrix into the cell interior.

[HIV-1 env glycoprotein gp120 and gp160 expressed in vaccinia virus system and their antigenicity analysis]

Human immunodeficiency virus type 1 (HIV-1) is the principal causative agent of AIDS that is an important concerns to human being health. The most important antigen of HIV-1 is its envelope glycoprotein gp160 (gp120 + gp41). By means of genetic engineering techniques, HIV-1 gp120 and gp160 were constructed and expressed in the recombinant vaccinia virus system under the control of bacteriophage T7 promoter or vaccinia virus p7.5 promoter. The results showed that the recombinant gp120 and gp160 expressed in this system exist in the form as glycoproteins, resuming the native epitope conformation of the viruses from which they were derived. These recombinant gp120 and gp160 could be recognized by the virus-specific neutralizing monoclonal antibodies. The findings suggested that the recombinant HIV-1 gp120 and gp160 could be used as a candidate recombinant protein vaccines.